Photometric determination of the mass accretion rates of pre-mainsequence stars - III. Results in the Large Magellanic Cloud

We present a multiwavelength study of three star-forming regions, spanning the age range 1-14 Myr, located between the 30 Doradus complex and supernova SN 1987A in the Large Magellanic Cloud (LMC). We reliably identify about 1000 pre-main-sequence (PMS) star candidates actively undergoing mass accretion and estimate their stellar properties and mass accretion rate ((M) over dot). Our measurements represent the largest (M) over dot data set of low-metallicity stars presented so far. As such, they offer a unique opportunity to study on a statistical basis the mass accretion process in the LMC and, more in general, the evolution of the mass accretion process around low-metallicity stars. We find that the typical (M) over dot of PMS stars in the LMC is higher than for galactic PMS stars of the same mass, independently of their age. Taking into account the caveats of isochronal age and (M) over dot estimates, the difference in (M) over dot between the LMC and our Galaxy appears to be about an order of magnitude. We review the main mechanisms of disc dispersal and find indications that typically higher (M) over dot are to be expected in low-metallicity environments. However, many issues of this scenario need to be clarified by future observations and modelling. We also find that, in the mass range 1-2M(circle dot), (M) over dot of PMS stars in the LMC increases with stellar mass as (M) over dot proportional to M-star(b), with b approximate to 1, i.e. slower than the second power law found for galactic PMS stars in the same mass regime